From 069e040e49c79b8ce1f8b73d85e02a05df6126b2 Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Sun, 19 Jan 2020 18:21:12 +0000
Subject: [PATCH]   * do for-loop unrolling after for-loop simplification,
 resolves #36589

git-svn-id: trunk@43999 -
---
 .gitattributes          |  1 +
 compiler/nflw.pas       | 36 +++++++++++++++++++-----------------
 tests/webtbs/tw36589.pp |  6 ++++++
 3 files changed, 26 insertions(+), 17 deletions(-)
 create mode 100644 tests/webtbs/tw36589.pp

diff --git a/.gitattributes b/.gitattributes
index 773768e870..3e8e4c83e2 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -17956,6 +17956,7 @@ tests/webtbs/tw3650.pp svneol=native#text/plain
 tests/webtbs/tw3653.pp svneol=native#text/plain
 tests/webtbs/tw36544a.pp svneol=native#text/pascal
 tests/webtbs/tw36544b.pp svneol=native#text/pascal
+tests/webtbs/tw36589.pp svneol=native#text/pascal
 tests/webtbs/tw3661.pp svneol=native#text/plain
 tests/webtbs/tw3666.pp svneol=native#text/plain
 tests/webtbs/tw3669.pp svneol=native#text/plain
diff --git a/compiler/nflw.pas b/compiler/nflw.pas
index 25fd4b98a0..139992eb73 100644
--- a/compiler/nflw.pas
+++ b/compiler/nflw.pas
@@ -1690,8 +1690,26 @@ implementation
 
          set_varstate(left,vs_written,[]);
 
+         { Make sure that the loop var and the
+           from and to values are compatible types }
+         if not(m_iso in current_settings.modeswitches) then
+           rangedef:=left.resultdef
+         else
+           rangedef:=get_iso_range_type(left.resultdef);
+
+         check_ranges(right.fileinfo,right,rangedef);
+         inserttypeconv(right,rangedef);
+
+         check_ranges(t1.fileinfo,t1,rangedef);
+         inserttypeconv(t1,rangedef);
+
+         if assigned(t2) then
+           typecheckpass(t2);
+         result:=simplify(false);
+
          { loop unrolling }
-         if (cs_opt_loopunroll in current_settings.optimizerswitches) and
+         if not(assigned(result)) and
+           (cs_opt_loopunroll in current_settings.optimizerswitches) and
            assigned(t2) and
            { statements must be error free }
            not(nf_error in t2.flags) then
@@ -1709,22 +1727,6 @@ implementation
                end;
            end;
 
-         { Make sure that the loop var and the
-           from and to values are compatible types }
-         if not(m_iso in current_settings.modeswitches) then
-           rangedef:=left.resultdef
-         else
-           rangedef:=get_iso_range_type(left.resultdef);
-
-         check_ranges(right.fileinfo,right,rangedef);
-         inserttypeconv(right,rangedef);
-
-         check_ranges(t1.fileinfo,t1,rangedef);
-         inserttypeconv(t1,rangedef);
-
-         if assigned(t2) then
-           typecheckpass(t2);
-         result:=simplify(false);
       end;
 
 
diff --git a/tests/webtbs/tw36589.pp b/tests/webtbs/tw36589.pp
new file mode 100644
index 0000000000..9d84e774a0
--- /dev/null
+++ b/tests/webtbs/tw36589.pp
@@ -0,0 +1,6 @@
+var k : longint;
+begin
+     for k:=1 downto 10 do
+     begin
+     end;
+end.